1. Field of the Invention
This invention relates to an improved sobriety interlock device. More particularly, it relates to a sobriety interlock device for use in vehicles and motorized machinery apparatus, the device incorporating anti-circumvention features and an improved sampling system to provide for more accurate measurements of the blood alcohol content of an unsupervised operator of a vehicle or motorized machinery apparatus.
2. Background of the Prior Art
Breathalyzer testing and sobriety interlock devices for use in vehicles (automobiles) and motorized machinery for industry are well known in the prior art. These types of devices work on a principle that the breath of a person who has consumed alcoholic beverages can be sampled to determine a corresponding blood alcohol content (blood to alcohol ratio) of that person. Using known levels of blood alcohol content, it can then be determined whether someone has too much alcohol in their system which would effect their ability to operate machinery or a vehicle. For instance, many states use a level of 0.08 as a percentage of blood alcohol content which acts as a presumption that a person is intoxicated and unable to drive a vehicle.
Early advancements in breathalyzer testing devices can be seen in U.S. Pat. No. 3,764,270 to Collier et al. wherein an alcohol concentration measuring apparatus is disclosed. In this reference it is noted that the operation of vehicles and machinery by persons intoxicated by alcohol is a major health problem in many places in the world and especially in the United States. The device of this prior art reference teaches that deep lung breaths are required to measure an accurate blood alcohol content from a gas sample or more accurately, the breath. Accordingly, improvements over then existing prior art devices are made in this Collier et al. reference that address measuring the alcohol concentration by ensuring a continuous and uninterrupted flow of gas from a subject using such device. However, it is not contemplated that this device could then be interfaced with the starting mechanism of a vehicle in the event that a predetermined threshold of the measured blood alcohol content is exceeded. This feature is clearly needed.
Subsequent devices seen in the prior art have addressed the need for a sobriety measuring device to be interfaced with a vehicle's starting mechanism—a so called “interlock” device. For instance, U.S. Pat. No. 3,831,707 to Takeuchi describes an early interlock device which takes a series of measurements to determine the temperature, humidity and alcohol concentration of the vehicle operator's breath. These measurements can be taken after the ignition switch of the vehicle (i.e., automobile) is engaged, thereby permitting the operator of the vehicle to warm up the car, by blowing into a sampling apparatus. Predetermined permitted ranges are set within the device for these three measurements. If the three readings fall within the permitted ranges (all three conditions pass), the automobile's transmission can be engaged and the car can be operated. If not (the test fails), the transmission of the automobile will not engage thereby preventing operation of the vehicle based upon an assumption that the operator is intoxicated and therefore lacking the required mental faculties to operate the vehicle. The temperature and humidity readings are used to sense that the air subjected to the sampling apparatus is in fact a human breath. Accordingly, these readings assist somewhat in the anti-circumvention of the interlock device. However, temperature and humidity can fluctuate substantially depending on the climate in which the vehicle is located and thereby effect the test being taken. Accordingly, there is a great need to improve upon temperature and humidity sensing systems that work in coincidence with the alcohol sensors to provide more accurate measurements for interlock devices. Further, other more sophisticated anti-circumvention features are needed in interlock devices to thwart attempts by users to fool the device thereby permitting their vehicle to be operated when it clearly should not.
Other advancements in the prior art for sobriety interlock devices have been made that do not directly address temperature and humidity sensing. In particular, advancements in measuring a continuous and uninterrupted flow of breath for the sampling device can be seen in U.S. Pat. No. 4,093,945 to Collier at al. which again addresses the need for sampling a deep lung breath since it is known that, absent some flow rate measurement equalization algorithm within an interfacing software program, deep lung breath samples are more apt to provide an accurate measurement of the blood alcohol content of the test taker than a short and shallow breath. The device of this prior art reference works to exclude breath samples that are not deep lung samples thereby requiring the individual taking the test to repeat the test until the device indicates that the breath sample was a deep lung breath sample. Unfortunately, this device can be difficult to use since not all individuals are capable of providing a deep lung sample needed to take the measurement. Improvements for measuring the flow rate of the breath samples are certainly needed. Such improvements should utilize an interfacing software program that can operate to equalize the breath samples through algorithmic offset calculations regardless of how deep or how shallow they are to provide the most accurate measurement possible.
Still other advancements in prior art interlock devices address operator identity. Since most states in the U.S. have already mandated the use of interlock devices for convicted DUI (driving under the influence of alcohol) offenders, operator identity of an unsupervised test can be critical. It is quite reasonable to assume that an inebriated vehicle operator may simply ask a sober person to take the test for them so that the vehicle starting mechanism can be engaged upon receiving a “pass” result since the test would be otherwise unsupervised. Although this act in itself is probably punishable by a fine or even incarceration in most states, it most likely has occurred and will continue to occur in the future. Accordingly, the inventions seen in U.S. Pat. No. 4,738,333 to Collier et al. and U.S. Pat. No. 4,809,810 to Elfman et al. and U.S. Published Application No. U.S. 2002/0084130 to Der Ghazarian et al. were developed to address operator identity so that the person mandated (by a Court for example) to take the sobriety test before the vehicle can be operated is the individual actually taking the test. It is important to note however, that these interlock devices are known to be more complicated and thereby require more maintenance/calibration, more expense and more sophisticated circuitry. Although there is a great need to ensure that the proper person is taking the sobriety test, such complicated and expensive devices may be overlooked and not employed due to their over-sophistication. There is clearly a need to keep sobriety interlock devices simple in their design but accurate in their measurement. Other, more simpler anti-circumvention technology should be used to ensure that drunk drivers are kept off the road. Development of a secure anti-circumvention interlock device that does not involve complex personal identity scans is clearly needed.
Most modern interlock devices include a few common elements: a power supply, a fuel cell (alcohol sensor), a sampling system (a breath intake channel leading to the fuel cell), a microprocessor to analyze the results of the test taken by the fuel cell and an output (a relay connected in series with the starter of the vehicle). In breath analyzer devices (those which are not used as interlock devices), output relays are not necessary since such devices are not intended to prevent the operation of a vehicle but merely used to give a blood alcohol content measurement. However, other common elements can be found, even though their uses may vary. Indicative of the use of a microprocessor in a breath analyzer device (but not that necessarily of an interlock device), as shown in U.S. Pat. No. 4,749,553 to Lopez et al., a microprocessor is employed to calculate the blood alcohol content by running an algorithm contained within the memory of the microprocessor using a plurality of signals-generated by taking a sample breath, including: an alcohol signal, a distance signal to compensate for diffusion of the exhaled breath, a pressure signal and a temperature signal. These types of signals are known as environmental signals and are helpful in securing a more accurate blood alcohol content measurement based upon ambient environmental conditions which may effect the measurement and give a false positive (a test fail). However, this device lacks important anti-circumvention features which are needed for use in interlock devices for preventing false measurements intended to “fool” the analyzing device. Anti-circumvention features are critically needed in interlocking devices since almost all measurements are taken in an unsupervised location. Further, the actions of DUI offenders under a court order to have the interlocking devices installed in their automobile will be under review. It will be imperative for the supervising agency (i.e., Probation Officer) to determine whether the interlocking devices have been circumvented, tampered with or not used when instructed (i.e., “rolling repeat tests”). Accordingly, use of data logs should be employed as a deterrent to the person mandated to use the device as well as for use in monitoring the life and proper function of the interlocking device.
One example of device circumvention includes using a gas source other than a current human breath, say from a balloon, to fool the device into thinking that an actual test is being made. One method to prevent such circumvention can be seen in the device of U.S. Pat. No. 4,902,628 to Blair. This device requires a positive and negative breath sample (blowing then sucking) to provide a measurement of the breath being tested and hence the blood alcohol content of such person. This device is first blown into by the person being tested, then the person is required to apply a suction after a short time lapse. Accordingly, a first and second signal are generated. If both signals are not recognized by a control means, a measurement will not be provided, the test will fail and the vehicle will not be permitted to start. This helps to ensure that an improper gas is not used to take a test on a device that merely requires the person to blow into such device. However, this type of device still could improved by employing enhanced anti-circumvention features.
In order that an accurate reading of the blood alcohol content is measured, it is important that the fuel cell not be exposed to too much pressure from a strong breath sample or too little pressure from a shallow or weak breath sample. Some prior art devices have attempted to address this problem. In those devices that utilize a valve upstream from the fuel cell, some have used a pressure transducer to control the opening and closing of the valve. This can be seen in U.S. Published Application No. U.S. 2003/0176803 to Gollar. In such device, the pressure transducer measures the pressure of the gas sample (human breath) and controls the opening of the valve in response to the measured pressure—a so called “constant volume” sampling system. This device integrates a pressure feedback signal to obtain a volumeric equivalent. The valve time opening varies from sample to sample based upon the measured pressure. In other words, the opening of the valve is directly dependent on the measurement taken by the pressure transducer.
A similar prior art device can be seen in U.S. Pat. No. 6,167,746 to Gammenthaler which utilizes a normally closed valve. The valve opens to control the volume of the breath sample by measuring the pressure of the breath flow through the device and, in response to the measured pressure, electronically controls the opening of the valve and diverts a portion of the breath flow into the fuel cell. A valve controller limits the duration of time that the valve is open based upon the measured pressure of the breath flow. In other words, the valve is dependent on the valve controller which in turn is dependent on the pressure measuring device.
An improved device is clearly needed wherein the valve works independently of the pressure transducer and permits a breath sample to pass there through without regard to the amount of pressure in the sample. The improved device should instead compensate for varying pressures through an algorithmic calculation and not through electronic valve controllers and pressure measuring devices.
It is clearly seen that an improved interlock device is needed which can provide for a more accurate blood alcohol content measurement all the while having the necessary anti-circumvention features that ensures individuals will use the device as intended. The device should be less complicated then those devices seen in the prior art such that greater ease of operation can still be achieved. Improved accuracy should be enjoyed through a microprocessor controlled valve working independently from a pressure sensitive component. The improved device should permit the logging of data relative to the operation of the device so that a supervising agency can review the log to see if circumvention or tampering of the device has occurred and to otherwise see that the device is working properly. Other features that monitor the status of the vehicle's movement would also help to ensure that circumvention is not attempted through idling of the vehicle while the person consumes alcohol away from the car that has already been started. Further, rolling repeat tests during operation of the automobile would help to ensure that alcohol is not being consumed by the driver during operation of the vehicle after it has been started (i.e., driving down the highway and consuming alcohol). Other improvements are also needed to ensure that the most accurate measurement is always provided. For instance, through the use of water filtering, moisture can be virtually eliminated from the breath vapor thereby avoiding moisture saturation of the fuel cell (the alcohol sensor). Improvements in temperature monitoring and temperature control of the device should also be practiced to ensure that the device works properly in cold weather climates.